The non-relational model expects us to duplicate information at each relevant place. It's hard to keep duplicated data updated and consistent. In return, by grouping relevant data together, document stores can offer more flexibility: You don't need to join rows, You don't need fixed schemas, Each data entry can have its own configuration of fields. This means there are no "tables" and "rows" in document stores. Instead, a data entry is called a document. Related documents are grouped in a collection.
